10,323
edits
Changes
Jump to navigation
Jump to search
mLine 18:
Line 18: − + − + Line 53:
Line 53: − + Line 70:
Line 70: − + − − − − − + − − − − − + − − − − Line 99:
Line 87: − + − + Line 121:
Line 109: − + − + − + − + − + − + − | 5 ft − | 28 in. − | − − − − + − − | 16 in. − | − − | − − + − + − | 3 ft − | 65 in. − | Estimate ''R''<sub>t</sub> , ''R''<sub>xo</sub> , and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems; reduced shoulder effects − | Not recommended; Res R<sub>mf</sub> / ''R''<sub>w</sub> − + − − | 40 in. − | − − | − − + − − − − − − − + − + − − − | Estimate ''R''<sub>t</sub> , ''R''<sub>xo</sub> , and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems; reduced shoulder effects − | Not recommended; Res > 250 Ω-m or ''R''<sub>mf</sub> / ''R''<sub>w</sub> − + − − − − − − − + − | 2.5 ft − | 16 in. − | − − − − + − + − − − − | Not recommended; ''R''<sub>mf</sub> / ''R''<sub>w</sub> > 2.5; − + − − | 16 in. − | − − − − + − − − − − + − + − − − − + − − − − − + − − − − − + − + + Line 258:
Line 178: − + − ! Vertical Resolution − ! Radius of Investigation − ! Applications − ! Limitations − + − − − − − + − − − − − + − + − + − + − + − + − − − − − + − − − − − + − − − − + Line 307:
Line 204: − + Line 317:
Line 214: − + Line 331:
Line 228: − + − ! Vertical Resolution+ − ! Radius of Investigation+ − ! Applications − + − − − − + − − − − + − − − − + − − − − + − − − Line 395:
Line 276: +
added Category:Methods in Exploration 10 using HotCat
* '''Storage capacity''' of the formation, which normally includes [[porosity]] and fluid saturations
* '''Storage capacity''' of the formation, which normally includes [[porosity]] and fluid saturations
* '''Fluid properties''', which include density, gas to oil ratio, API gravity, water resistivity and salinity, temperature, and pressure
* '''Fluid properties''', which include density, gas to oil ratio, [[API gravity]], water resistivity and salinity, temperature, and pressure
* '''Geological setting''', which may include structural or stratigraphic dip, facies characteristics, and reservoir heterogeneities
* '''Geological setting''', which may include structural or stratigraphic [[dip]], facies characteristics, and reservoir heterogeneities
The basic open hole wireline logging devices can be divided into four general groups, as shown in Table 1. The ''correlation and lithology'' devices are used primarily to correlate between wells and to discriminate reservoir from nonreservoir rocks. The ''resistivity'' devices are used to determine formation resistivity at varying distances from the wellbore, which is used for correlation and the determination of water saturation. The ''lithology and porosity'' devices are used to determine both lithology and porosity. A variety of ''auxiliary'' tools are used to make special logging measurements. (For more on tool specifications, see [[Basic tool table]].)
The basic open hole wireline logging devices can be divided into four general groups, as shown in Table 1. The ''correlation and lithology'' devices are used primarily to correlate between wells and to discriminate reservoir from nonreservoir rocks. The ''resistivity'' devices are used to determine formation resistivity at varying distances from the wellbore, which is used for correlation and the determination of water saturation. The ''lithology and porosity'' devices are used to determine both lithology and porosity. A variety of ''auxiliary'' tools are used to make special logging measurements. (For more on tool specifications, see [[Basic tool table]].)
| Formation Tester
| Formation Tester
|-
|-
| Dipmeter
| [[Dipmeter]]
|-
|-
| Borehole Televiewer
| Borehole Televiewer
| Spontaneous potential (SP) || 6–10 ft || N/A || Well-to-well correlation, estimate ''R''<sub>w</sub> , and indicate [[permeability]] || Does not work in oil-based mud and ''R''<sub>mf</sub> and ''R''<sub>w</sub> must contrast
| Spontaneous potential (SP) || 6–10 ft || N/A || Well-to-well correlation, estimate ''R''<sub>w</sub> , and indicate [[permeability]] || Does not work in oil-based mud and ''R''<sub>mf</sub> and ''R''<sub>w</sub> must contrast
|-
|-
| Gamma ray
| Gamma ray || [[length::2 ft]] || [[length::12 in]] || Well-to-well correlation and estimate ''V''<sub>sh</sub> || Sensitive to hole size changes
| [[length::2 ft]]
| [[length::12 in]]
| Well-to-well correlation and estimate ''V''<sub>sh</sub>
| Sensitive to hole size changes
|-
|-
| Spectral gamma ray
| Spectral gamma ray || [[length::3 ft]] || [[length::16 in]] || Well-to-well correlation and estimate ''V''<sub>sh</sub> || Sensitive to hole size changes
| [[length::3 ft]]
| [[length::16 in]]
| Well-to-well correlation and estimate ''V''<sub>sh</sub>
| Sensitive to hole size changes
|-
|-
| Photoelectrical effect (Pe)
| Photoelectrical effect (Pe) || [[length::2 in]] || [[length::2 in]] || Identify lithology and well-to-well correlation || Does not work in barite mud, is a pad device, and uses a radioactive source
| [[length::2 in]]
| [[length::2 in]]
| Identify lithology and well-to-well correlation
| Does not work in barite mud, is a pad device, and uses a radioactive source
|}
|}
===Gamma ray===
===Gamma ray===
Gamma rays tools measure the natural radioactivity of the formation. This radioactivity is emitted primarily from potassium in the structure of clay minerals, radioactive salts in the formation waters, radioactive salts bound to the charged surfaces of clay minerals, potassium associated with feldspars, and radioactive minerals associated with igneous rocks and rock fragments. The gamma ray response is used for correlation of formations between wells and for estimating volume shale and/or volume clay minerals.
Gamma rays tools measure the natural radioactivity of the formation. This radioactivity is emitted primarily from potassium in the structure of clay minerals, radioactive salts in the formation waters, radioactive salts bound to the charged surfaces of clay minerals, potassium associated with feldspars, and radioactive minerals associated with [[igneous rock]]s and rock fragments. The gamma ray response is used for correlation of formations between wells and for estimating volume shale and/or volume clay minerals.
An advanced version of the gamma ray tool, called the ''spectral gamma ray'', breaks down or segments the detected gamma rays by their different energies using spectral analysis techniques. These segments correspond to the radioactive families of potassium, uranium, and thorium. Uranium frequently occurs as a precipitated salt deposited in a formation from waters having flown through that formation. When this occurs, the uranium counts disguise radioactivity due to mineralogy. The use of the spectral tool allows the removal of gamma ray counts caused by uranium, typically permitting more accurate use of the remaining gamma rays for determining lithology, volume shale, or volume clay. In some local areas, ratios of potassium to thorium have been successfully used to determine some clay types. However, this clay typing has not proven particularly universal and should be attempted with much caution.
An advanced version of the gamma ray tool, called the ''spectral gamma ray'', breaks down or segments the detected gamma rays by their different energies using spectral analysis techniques. These segments correspond to the radioactive families of potassium, uranium, and thorium. Uranium frequently occurs as a precipitated salt deposited in a formation from waters having flown through that formation. When this occurs, the uranium counts disguise radioactivity due to [[mineralogy]]. The use of the spectral tool allows the removal of gamma ray counts caused by uranium, typically permitting more accurate use of the remaining gamma rays for determining lithology, volume shale, or volume clay. In some local areas, ratios of potassium to thorium have been successfully used to determine some clay types. However, this clay typing has not proven particularly universal and should be attempted with much caution.
Typical presentations of gamma ray measurements are shown in the logs in both [[::file:basic-open-hole-tools_fig1.png|Figures 1]] and [[:file:basic-open-hole-tools_fig2.png|2]]. (For information on the cased hole gamma ray tool, see [[Basic cased hole tools]])
Typical presentations of gamma ray measurements are shown in the logs in both [[::file:basic-open-hole-tools_fig1.png|Figures 1]] and [[:file:basic-open-hole-tools_fig2.png|2]]. (For information on the cased hole gamma ray tool, see [[Basic cased hole tools]])
| colspan=5 | Dual induction
| colspan=5 | Dual induction
|-
|-
| Deep
| Deep || 7 ft || 50 in. || rowspan=3 | Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems || rowspan=3 | Not recommended; Res > 200 Ω-m or ''R''<sub>mf</sub> / ''R''<sub>w</sub> < 2.5
| 7 ft
|-
| 50 in.
| Medium || 5 ft || 28 in.
| Estimate ''R''<sub>t</sub> , ''R''<sub>xo</sub> , and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems
|-
| Not recommended; Res > 200 Ω-m or ''R''<sub>mf</sub> / ''R''<sub>w</sub>
| Shallow<sup>a</sup> || 2.5 ft || 16 in.
|-
|-
| Medium
| colspan=5 | Phasor induction
|
|-
|-
| Shallow<sup>a</sup>
| Deep || 3 ft || 65 in. || rowspan=3 | Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems; reduced shoulder effects || rowspan=3 | Not recommended; Res > 250 Ω-m or R<sub>mf</sub> / ''R''<sub>w</sub> < 2.5
| 2.5 ft
|-
|-
| Phasor induction
| Medium || 3 ft || 40 in.
|-
|-
| Deep
| Shallow<sup>a</sup> || 2.5 ft || 16 in.
|-
|-
| Medium
| colspan=5 | High resolution induction
| 3 ft
|-
|-
| Shallow<sup>a</sup>
| Deep || 2.5 ft || 95 in. || rowspan=3 | Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems; reduced shoulder effects || rowspan=3 | Not recommended; Res > 250 Ω-m or ''R''<sub>mf</sub> / ''R''<sub>w</sub> < 2.5
| 2.5 ft
| 16 in.
|
|
|-
|-
| High resolution induction
| Medium || 2.5 ft || 60 in.
|-
|-
| Deep
| Shallow<sup>a</sup> || 2.5 ft || 16 in.
| 2.5 ft
| 95 in.
|-
|-
| Medium
| AIT* || 4 ft. 2 ft. 1 ft || 10 in., 20 in., 30 in., 60 in., 90 in. || Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively fresh and oil mud systems; reduced shoulder and rugosity effects || Not recommended; Res > 200 Ω-m or ''R''<sub>mf</sub> / ''R''<sub>w</sub> < 2.5
| 2.5 ft
| 60 in.
|
|
|-
|-
| Shallow<sup>a</sup>
| colspan=5 | Dual laterolog
|
|-
|-
| Dual laterolog
| Deep || 2 ft || 45 in. || rowspan=3 | Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively salty mud || rowspan=3 | Not recommended; ''R''<sub>mf</sub> / ''R''<sub>w</sub> > 2.5; does not work in oil based mud
|-
|-
| Deep
| Shallow || 2 ft || 16 in.
| 2 ft
| 45 in.
| Estimate ''R''<sub>t</sub> , ''R''<sub>xo</sub> , and ''D''<sub>''i''</sub> in relatively salty mud
|-
|-
| Shallow
| Microresistivity || colspan=2 | (See below)
| 2 ft
|
|-
|-
| Microresistivity
| ARI* || 8 in. || 4 ft || Estimate ''R''<sub>t</sub>, ''R''<sub>xo</sub>, and ''D''<sub>''i''</sub> in relatively salty mud, locate fractures || Resistivity range 0.2 to 100,000 Ω-m
| (See below)
|
| Does not work in oil-based mud
|-
|-
| Micro SFL
| Micro SFL || 2-3 in. || 1–4 in.
| 2-3 in.
| [[Permeability]] and moved hydrocarbon indicator; estimate ''R''<sub>''xo''</sub> || No oil-based muds
| 1–4 in.
| [[Permeability]] and moved hydrocarbon indicator; estimate ''R''<sub>''xo''</sub>
| No oil-based muds
|-
|-
| Microlaterolog
| Microlaterolog || 2 in. || 4 in. || Permeability and moved hydrocarbon indicator; estimate ''R''<sub>''xo''</sub> || No oil-based muds
| 2 in.
| 4 in.
| Permeability and moved hydrocarbon indicator; estimate ''R''<sub>''xo''</sub>
| No oil-based muds
|-
|-
| Microlog
| Microlog || 2-4 in. || 1-2 in. || Permeability and moved hydrocarbon indicator; estimate ''R''<sub>xo</sub> || No oil-based muds
| 2-4 in.
| 1-2 in.
| Permeability and moved hydrocarbon indicator; estimate ''R''<sub>xo</sub>
| No oil-based muds
|}
|}
<sup>a</sup><sub>Shallow measurements do not work in oil-based muds.</sub>
<sup>a</sup><sub>Shallow measurements do not work in oil-based muds.</sub><br>
<sup>b</sup><sub>The ohm-meter (Ω-m) is a unit of measurement of resistance.</sub>
<sup>b</sup><sub>The ohm-meter (Ω-m) is a unit of measurement of resistance.</sub><br>
<sup>*</sup><sub>Mark of Schlumberger</sub><br>
===Induction===
===Induction===
|+ {{table number|4}}Resolution and application of porosity and lithology devices
|+ {{table number|4}}Resolution and application of porosity and lithology devices
|-
|-
! Tool
! Tool || Vertical Resolution || Radius of Investigation || Applications || Limitations
|-
|-
| Compensated density
| Compensated density || 18 in. || 8 in. || Estimate porosity || Pad contact device
| 18 in.
| 8 in.
| Estimate porosity
| Pad contact device
|-
|-
| Compensated neutron
| Compensated neutron || 2 ft || 10 in. || Estimate porosity and identify presence of gas || Needs environmental corrections; sensitive to standoff from wall
| 2 ft
| 10 in.
| Estimate porosity and identify presence of gas
| Needs environmental corrections; sensitive to standoff from wall
|-
|-
| Sonic
| IPL* (Integrated Porosity Lithology) || 1 ft || -- || Estimate porosity and identify presence of gas, thin bed evaluation, shalt sand evaluation || Needs environmental corrections; sensitive to standoff from wall
| 2 ft
|-
| Typically 6 in.
| Sonic || 2 ft || Typically 6 in. || Measure compressional velocity and estimate porosity || Sensitive to compressibility
| Measure compressional velocity and estimate porosity
|-
| Sensitive to compressibility
| FWS (monopole) || 4 ft || Typically 6 in. || Measure compressional and shear velocities and estimate porosity || Cannot measure shear velocity when shear velocity > mud velocity
|-
|-
| FWS (monopole)
| Dipole sonic || 4 ft || Typically 12 in. || Measure shear velocity || —
| 4 ft
| Typically 6 in.
| Measure compressional and shear velocities and estimate porosity
| Cannot measure shear velocity when shear velocity > mud velocity
|-
|-
| Dipole sonic
| CMR* (Combinable Magnetic Resonance) || 6 in. || 1 in. || Porosity, pore size distribution, permeability || Minimum 6.5 in. wellbore
| 4 ft
| Typically 12 in.
| Measure shear velocity
| —
|-
|-
| Photoelectrical effect (Pe)
| Photoelectrical effect (Pe) || 2 in. || 2 in. || Identify lithology and correlation || Does not work in barite mud and pad contact tool
| 2 in.
| 2 in.
| Identify lithology and correlation
| Does not work in barite mud and pad contact tool
|}
|}
<sup>* Mark of Schlumberger</sup><br>
===Density===
===Density===
===Compensated neutron===
===Compensated neutron===
Compensated neutron devices measure the hydrogen index of the formation using a radioactive neutron source that bombards the formation with fast-moving neutrons. Neutrons collide with atoms of the formation, transferring their energy through these collisions. The most efficient transfer of energy occurs with hydrogen atoms because the mass of hydrogen is approximately the same as the mass of a neutron. Two detectors count the number of deenergized (thermal) neutrons returning from the formation. The ratio of the detector count rates is primarily related to the hydrogen index or the apparent water-filled porosity.
Compensated neutron devices measure the [[hydrogen index]] of the formation using a radioactive neutron source that bombards the formation with fast-moving neutrons. Neutrons collide with atoms of the formation, transferring their energy through these collisions. The most efficient transfer of energy occurs with hydrogen atoms because the mass of hydrogen is approximately the same as the mass of a neutron. Two detectors count the number of deenergized (thermal) neutrons returning from the formation. The ratio of the detector count rates is primarily related to the hydrogen index or the apparent water-filled porosity.
The source and detectors are mounted in a mandrel that, ideally, is pressed against the borehole to minimize the influence of the high apparent porosity of the borehole. This measurement is very sensitive to tool standoff, hole size, temperature, and salinity. Environmental corrections are highly recommended before attempting to interpret results. Gas has a very low hydrogen index compared to water, which causes the tool to report abnormally low porosities in gas-bearing formations. When used in conjunction with density measurements, gas-bearing intervals are often easy to identify. A typical presentation of a compensated neutron measurement is shown in the log in [[:Image:basic-open-hole-tools_fig2.png|Figure 2]].
The source and detectors are mounted in a mandrel that, ideally, is pressed against the borehole to minimize the influence of the high apparent porosity of the borehole. This measurement is very sensitive to tool standoff, hole size, temperature, and salinity. Environmental corrections are highly recommended before attempting to interpret results. Gas has a very low hydrogen index compared to water, which causes the tool to report abnormally low porosities in gas-bearing formations. When used in conjunction with density measurements, gas-bearing intervals are often easy to identify. A typical presentation of a compensated neutron measurement is shown in the log in [[:Image:basic-open-hole-tools_fig2.png|Figure 2]].
Two versions of the compressional sonic device are available: the compensated sonic and the full waveform sonic (FWS). The full waveform sonic contains an array of receivers that are used to determine both compressional and shear velocities. Sonics are available in a variety of transmitter-to-receiver spacings from 3 to [[length::12 ft]] or more. The longer spacings are capable of investigating deeper into the formation. Both the conventional sonic and the full waveform sonic devices are used to measure compressional velocity. A typical presentation of compressional sonic measurements is shown in the log in [[:Image:basic-open-hole-tools_fig1.png|Figure 1]].
Two versions of the compressional sonic device are available: the compensated sonic and the full waveform sonic (FWS). The full waveform sonic contains an array of receivers that are used to determine both compressional and shear velocities. Sonics are available in a variety of transmitter-to-receiver spacings from 3 to [[length::12 ft]] or more. The longer spacings are capable of investigating deeper into the formation. Both the conventional sonic and the full waveform sonic devices are used to measure compressional velocity. A typical presentation of compressional sonic measurements is shown in the log in [[:Image:basic-open-hole-tools_fig1.png|Figure 1]].
Shear velocities are used to determine mechanical properties of the formations and to determine Poisson's ratio for use in interpreting seismic data. Shear velocities can be determined from the FWS (monopole), the dipole sonic, or the quadrupole sonic. The monopole sonic is not able to measure shear velocities when the shear velocity of the formation is slower than the compressional velocity of the mud. Mud interval transit times are typically in the 190 μsec/ft range. When this condition is not met, no shear energy is refracted toward the receivers, making shear velocity measurements impossible. The dipole overcomes this limitation by directly exciting shear flexural energy in the formation regardless of the mud velocities.
Shear velocities are used to determine mechanical properties of the formations and to determine Poisson's ratio for use in interpreting [[seismic data]]. Shear velocities can be determined from the FWS (monopole), the dipole sonic, or the quadrupole sonic. The monopole sonic is not able to measure shear velocities when the shear velocity of the formation is slower than the compressional velocity of the mud. Mud interval transit times are typically in the 190 μsec/ft range. When this condition is not met, no shear energy is refracted toward the receivers, making shear velocity measurements impossible. The dipole overcomes this limitation by directly exciting shear flexural energy in the formation regardless of the mud velocities.
===Photoelectric effect===
===Photoelectric effect===
|+ {{table number|5}}Resolution and applications of auxiliary devices
|+ {{table number|5}}Resolution and applications of auxiliary devices
|-
|-
! Tool
! Tool || Vertical Resolution || Radius of Investigation || Applications
|-
| Calipers || N/A || N/A || Determine borehole diameter
|-
|-
| Calipers
| Formation testers || 0.5 in. || N/A || Measure formation pressures and recover formation fluid samples
| N/A
| N/A
| Determine borehole diameter
|-
|-
| Formation testers
| Dipmeters || 0.4 in. || 1 in. || Structural dip, stratigraphic dips, and hole geometry
| 0.5 in.
| N/A
| Measure formation pressures and recover formation fluid samples
|-
|-
| Dipmeters
| Formation microscanner || 0.2 in. || 1 in. || Structural dip, stratigraphic dips, formation images, and hole geometry
| 0.4 in.
| 1 in.
| Structural dip, stratigraphic dips, and hole geometry
|-
|-
| Formation microscanner
| Televiewer || 0.5 in. || 0 in. || Structural dip, stratigraphic dips, formation images, and hole geometry
| 0.2 in.
| 1 in.
| Structural dip, stratigraphic dips, formation images, and hole geometry
|-
|-
| Televiewer
| Formation MicroImager || 0.2 in. || 0 in. || As for Televiewer
| 0.5 in.
| 0 in.
| Structural dip, stratigraphic dips, formation images, and hole geometry
|}
|}
[[Category:Wireline methods]] [[Category:Pages with badly formatted tables]]
[[Category:Wireline methods]] [[Category:Pages with badly formatted tables]]
[[Category:Methods in Exploration 10]]